Synthesis of three partially fluorinated alkanesulfonic acids as potential fuel-cell electrolytes

The sknpie and effective syntheses of CH2FCH2SOSH, CF,CH$O,H, and CHF2CFzCH2S03H have been achieved with 18.8%, 34.1%, and 33.7% overall yleids. The low molecular weighl partlaly fluorlnated aikanesuifonlc aclds containing a-methyiene groups can be prepared from the p-toluemsulfonates of the correspondlng alcohols, via a reaction with benzyl mercaptan, followed by an oxidative chlorination of the resulting sulfides, with subsequent hydrolysis of the sulfonyl chlorlde formed R&H20H (TsCi) R,CH20Ts (CIH,CH2SNa + DMF) RfCH,SOsH. The reaction of partially fiuorlnated alkyl halides with sodium sulflte (Strecker's method) proved to be inefflcient (very low yields) and unreilabie. The sulfonate salts formed are difficult to recover and purlfy: &CH2X 4NafiO, R,CH2SOSNa R,CH$O,H. RfCH2SCH2CIHI (CI2 + H20) -'+ R&H2S02CI (H2O + A)